The present invention is directed to field of apparatus for the forming of sand cores and molds for use in casting of metals in foundries. The general concepts involved in the formation of such molds for the casting of metal are so well known as to not require any specific description of the principles.
Preparation of sand molds and cores for the metal casting industry have a number of desirable goals. Among these are the following:
The process should be one of continuous operation so that any stop and start motion throughout the system is minimized and preferably totally eliminated. As is known the quantity of binder that must be added to sand in the forming of such molds depends to a degree upon the speed with which the sand is utilized after blending. The placement of sand-binders into molds substantially immediately after blending permits use of minimum amounts of binder to sand ratio thus decreasing costs. While not limited thereto, it is contemplated that the apparatus of the invention will find its principal use in conjunction with so-called no-bake binders. However, other binders may be used which makes use of microwave curing, heat or chemical treatment to bring about cure as well as the use of the preferred no-bake binders.
The equipment which is involved in preparing such sand molds also desirably occupies as small an amount of floor space as possible.
In accordance with the present invention, apparatus is provided utilizing an endless chain type conveyor system which moves a plurality of pattern carriers or mold boxes about the endless conveyor. At the upper portion of the conveyor, the appropriate patterns are inserted in the pattern carriers and then through the use of a sand filling arrangement, flasks surrounding the patterns are filled with a sand-binder mix. The movement of the chain carries the flask along beneath the filling apparatus and at a predetermined point a scraper or strike-off member is actuated to sweep across the surface of the mold to provide a uniform level of semi-compacted sand. The excess sand is swept into the following flask which is then subsequently filled as it passes beneath the sand spout. The filled flask then progresses along the endless conveyor through such additional processing steps as are required for compacting and removal of excess or loose sand -- such as tamping and sweeping. Cure accelerating means may also be used as the now filled flasks progress along the upper course of the conveyor. As the now filled and open topped flask begins to turn about the end wheel of the endless conveyor, the sand-binder surface is engaged by a holding means such as second belt conveyor which has a synchronous movement with the flask and chain drive so that it provides at least in partial a closure for the top of the flask holding the partially set sand-binder mixture within the flask. In the preferred embodiment, this endless belt then continues in engagement with the open and inverted end of the flask as the flask passes beneath the lower course of the endless chain conveyor. After the sand-binder mix is set sufficiently to retain its shape, a draw station is passed wherein the sand mold is removed from the flask and passes along the conveyor to a next work station.
The invention will be best understood in conjunction with the following drawings wherein: